Technical Abstract:
Flavobacterium columnare is pathogenic to most if not all species of freshwater fish. The ubiquitous nature of F. columnare makes understanding the disease and disease agent troublesome. The host-pathogen-environment relationship theory described by Snieszko can be applied to our understanding of this important fish pathogen. Age, species, strain(s), nutritional and immunological status of the host appear relevant to the establishment of columnaris disease. The pathogen including exposing dose, virulence and genetic type (strain) are also important to disease development. Environmental conditions including temperature and water quality and other stressor(s) (e.g. population density; parasitism) influence the development of columnaris disease in laboratory and field settings. Our experiences and other published examples will be used to illustrate these concepts in relation to F. columnare challenge models for studying virulence, pathogenesis, immunity and control strategies (e.g., vaccination and therapeutics).